Log stems are typically about 60 feet in length. The 60-foot length is dictated by state road restrictions. That is, a log stem is the felled tree length that can be loaded onto trucks and hauled to a lumber mill. Most state requirements prohibit load lengths longer than 60 feet, and thus the stems are cut to that length and lumber mills are set up to handle logs 60 feet and shorter (the shorter stems, of course, resulting from trees that are shorter than 60 feet and also the balance of a much longer stem that has had 60 feet cut from it).
Over the years there has been an increasing awareness of the huge waste of wood from a tree. A tree that is standing has an enormous potential for usable lumber. However, every cut that is made reduces the options of the cutting pattern that can be fit to the log. Trees are first cut into stems, the stems into segments in a bucking operation at the sawmill site, the segments are cut into cants and the cants into specific lumber pieces, e.g. 1.times.4's, 2.times.4's, 2.times.6's, and so on, all having varying lengths of four feet, six feet, eight feet, etc. A tree that is standing will have a far greater potential than the lumber typically produced from that tree because of errors in making these cuts.
Improvements have been made in the analysis of the lumber potential for the segments. That analysis dictates the selection of the cutting pattern to thereby achieve substantially improved lumber production. One of the developments notable for accomplishing this improved analysis is REAL SHAPE.TM.. This is a scanning and computer analyzing process that extensively measures the log segment to enable a detailed model of the log to be created by the computer. The computer is programmed with the capability of fitting to that model the ideal cutting pattern for maximizing the value of the lumber produced. REAL SHAPE.TM. is made available by the Applied Theory division of U.S. Natural Resources, Inc., which division is located in Corvallis, Oreg.
The problem with the heretofore applied analysis of a log segment is that it is not made soon enough. A very substantial lumber potential for the log stem may already be lost when the stem is cut into segments.
Heretofore attempts have been made to analyze the log stem for determining the cutting of that stem into segments of optimal length. However, because of a number of inherent limitations, such analysis has been very crude and far short of the accuracy needed to consistently accomplish the desired potential.
The known prior analyzing systems all have had a common flaw. They attempt to scan or measure the log by moving the log stem through or past stationary scanners. Whereas log segments are successfully measured in that manner, log stems are a different matter. In a 60-foot length, the inconsistency of the log configuration along its length is particularly in evidence. For example, the log may taper from a large-end diameter of three feet and larger down to a small-end diameter of one foot and smaller. Along the length are twists and bends. Regardless of the conveying mechanism used for conveying the stem past the scanners, the log stem, which is very heavy and yet flexible, bends and twists as it is moved. The scanner depends on the log stem being fixed relative to the conveyor and thus scanning in this manner is not dependable and cannot be relied on to determine the optimum cutting pattern.
Futhermore, one might assume that only the log length needs to be known to determine the desired segment lengths. That is definitely not the case. For example, one portion of the log may be particularly suited for obtaining a precise number of 2.times.10's fourteen feet long, and 2.times.10's fourteen feet long may be at a premium price. Under the prior methods, that segment may be inadvertently cut into an eight-foot length or even split between two other segments, etc. This simple oversight is costly as once the segments are cut, the loss cannot be recovered.
Also to be considered is the practical constraint of applying a solution to existing lumber mills. Changing the in-feed of a log or otherwise creating a need for additional yard space can be costly or even prohibitive in applying a solution to existing lumber mills. Such changes are preferably to be avoided or minimized.